Fire detecting cable



y 947. D. R. WHEELER 2,423,537

FIRE DETECTING CABLE Filed March 5, 19-43 JOC'AZ Y 1101 66 Z62"INVENTOR.

AYTORNKYI Patented July 8, 1947 uNnao STATES PATENT ornca FIRE DETECTINGCABLE Dock R. Wheeler, Shreveport, La.

Application March 5, 1943, Serial No. 478,152

Claims.

My invention relates to electric circuits, and has. among its objectsand advantages the provision of an improved fire detecting cable which=may be produced at a low cost, folded and easily handled withoutdamage, and in which the cable structureis such as to provide arelatively compact construction.

In the accompanying drawings:

Figure 1 is a fragmentary view of a cable in accordance with myinvention and in association with an electrically energized signal.

Figure 2 is an enlarged sectional view along the line 2-2 of Fi ure 1.

Figure 3 is a perspective view of a conductor ;for illustration, Figure1 illustrates a conductor wire 36 enclosed in a second conductor i2 andseparated therefrom by insulation 46. The insulation 46 is in the natureof a ribbon wrapped spirally about the wire 36 and the conductor I2 isof ribbon like contour and spirally wound over the insulation 46 but ina reverse direction. Both conductors 36 and i2 are of fusibie'alloywhich fuses at a relatively low temperature. Such materials are wellknown in the art.

Asignal, such as a conventional electric bell embodying a bell i6 andthe common electromagnetic operating mechanism in a housing i8, has oneterminal connected through a wire 20 with the center conductor wire 36and the other terminal connected, through a wire 22 with the exteriorribbon like conductor i2. A source of electric current, such as abattery, 24 is interposed in the wire 22. Thus, when the cable is innormal and proper condition the circuit through the bell remains openbut when the cable is subjected to an abnormal condition so as to causefusion, of the exterior conductor i2 and effect contact between the sameand the inner conductor wire 36 the circuit is closed and the bell iscaused to ring and indicate such fusion. The insulation is wrapped withits convolution so spaced as to provide ample clearance for fusedmaterial from either conductor to flow into contact with the other. Theconvolutions of the metal tape constituting the conductor l 2 are closewound so that this conductor constitutes, a housing for the insulation46. This insulation may be cemented to the conductor 36, if desired.

On the inner face .of the conductor 12 is applied a thin body or strip28 of noncorroding material which fuses at a low temperature. This stripacts as a protector which provides better contact between the fusedconductors 36 and I2,

particularly in cases where thesetwo conductors might become corrodedafter a period of years. A fabric wrapper or braid 30 is applied overthe conductor i2.

In wrapping the conductor l2 about the insulated conductor 36, the cablestructure 26 comprises a unit line of relatively small proportions, oneof which eliminates necessity of insulating and connecting as a unit twoparallel conductors. The cable structure is easy to handle and may berolled without harm to the line.

In Figure 4, the conductor 36 is provided with a ribbon 38 of spirallywound insulation. A mev tallic sleeve 40 of braided wire encloses theinsulation 38, the conductor 36 and the sleeve 40 corresponding to theconductors iii and i2, re-

spectively.

The construction of Figure 5 diilers from that of Figure 6' only in thata protective sleeve 42 is applied over the conductor sleeve 40. Theconductors 36 and 40 are.also fusible at low temperatures.

In Figure 6, the conductor 44 is enclosed in a covering 46 of insulatingmaterial in the nature of a ribbon close wound spirally about theconductor. The ribbon is perforated at 48 to allow fused material fromthe two conductors to make contact.

In Figure 7, the conductor 50 is enclosed in a braided insulating ribbon52 wound spirally thereon. This braid is sufilciently open to permitfree passage of fused material.

The covering 30 of Figure 1 may constitute fabric or metal wire. A wirecovering affords protectlon against gnawing animals. Obviously all thecable devices may be enclosed in such a protective covering, withinsulation provided wherever necessary. All the forms are identical withrespect to the compact arrangement of the parts when considered in crosssection.

Without further elaboration, the foregoing will so fully explain myinvention, that others may, by applying current knowledge, readily adaptthe same for use under various conditions of service.

I claim:

1. A cable of the type described comprising first and second conductorseach of material for, and said insulation being provided withinterstices through which fusion of the conductors will make contacttherebetween.

2. The invention as in claim 1 wherein a noncorroding strip which fusesat'low temperature is provided on said second conductor.

3. The invention as in claim 1 wherein a protective noncorroding stripwhich fuses at low temperature is provided onsaid second conductoradjacent said insulation.

4. In a cable ofthe character described, an

inner conductor, insulation on said conductor, an outer conductor woundspirally on said insulation, and a strip of noncorroding materialfusible at a relatively low temperature secured to the inner face of thespirally wound conductor, said insulation being providedwith'interstices disposed to provide spacing-whereby fusing of thenoncorroding and fusiblestrip will effect electrical connection betweenthe inner and outer- N conductors.

5. In a cable of-the character described, an

inner conductor, an outer conductor, and insulating spacing meansbetweensaid conductor 4 provided with interstices forming separated pockets,supporting the conductors in normally noncontacting relationship; saidconductors being formed of material which is fusible at relatively 5 lowtemperature, the insulating spacing means provided with open areasbetween the two spaced conductors through which the fused material ofthe conductors may pass to make contactwhen the fusion point intemperature of the conductors is reached.

DOCK R. WHEELER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,235,028 Harsch July 31, 19171,283,260 Montgomery Oct. 29, 1918 1,779,610 Lyndon Oct. 28, 1930 12,048,271 Lindsey July 21. 1936 1,129,358 Mitchell Feb. 23, 1915 V1,608,18 Rumble Nov. 23. 1926 1,738,828 Jackson Dec. 10, 1929 1,962,041Spong June 5, 1934 2,161,395 Wheeler June 6, 1939 FOREIGN PATENTS VNumber Country Date France June 15, 1925

